ABSTRACT BACKGROUND: The term dangerous universal blood donor refers to potential agglutination of the erythrocytes of non-O recipients due to plasma of an O blood group donor, which contains high titers of anti-A and/or anti-B hemagglutinins. Thus, prior titration of anti-A and anti-B hemagglutinins is recommended to prevent transfusion reactions. OBJECTIVE: The aim of this study was to estimate the frequency of dangerous universal donors in the blood bank of Belo Horizonte (Fundação Central de Imuno-Hematologia - Fundação Hemominas - Minas Gerais) by determining the titers of anti-A and anti-B hemagglutinins in O blood group donors. METHOD: A total of 400 O blood group donors were randomly selected, from March 2014 to January 2015. The titers of anti-A and anti-B hemagglutinins (IgM and IgG classes) were obtained using the tube titration technique. Dangerous donors were those whose titers of anti-A or anti-B IgM were ≥128 and/or the titers of anti-A or anti-B IgG were ≥256. Donors were characterized according to gender, age and ethnicity. The hemagglutinins were characterized by specificity (anti-A and anti-B) and antibody class (IgG and IgM). RESULTS: Almost one-third (30.5%) of the O blood group donors were universal dangerous. The frequency among women was higher than that of men (p-value = 0.019; odds ratio: 1.66; 95% confidence interval: 1.08-2.56) and among young donors (18-29 years old) it was higher than for donors between 49 and 59 years old (p-value = 0.015; odds ratio: 3.05; 95% confidence interval: 1.22-7.69). There was no significant association between dangerous universal donors and ethnicity, agglutinin specificity or antibody class. CONCLUSION: Especially platelet concentrates obtained by apheresis (that contain a substantial volume of plasma), coming from dangerous universal donors should be transfused in isogroup recipients whenever possible in order to prevent the occurrence of transfusion reactions.

BACKGROUND: The RHD gene is highly polymorphic, which results in a large number of RhD variant phenotypes. Discrepancies in RhD typing are still a problem in blood banks and increase the risk of alloimmunization. In this study, the RhD typing strategy at a blood bank in Brazil was evaluated.METHODS: One-hundred and fifty-two samples typed as RhD negative and C or E positive by routine tests (automated system and indirect antiglobulin test using the tube technique) were reevaluated for RhD status by three methods. The method with the best performance was implemented and evaluated for a period of one year (n = 4897 samples). Samples that were D positive exclusively in the confirmatory test were submitted to molecular analysis.RESULTS: The gel test for indirect antiglobulin testing with anti-D immunoglobulin G (clone ESD1) presented the best results. Seventy samples (1.43%) previously typed as RhD negative showed reactivity in the gel test for indirect antiglobulin testing and were reclassified as D positive. D variants that may cause alloimmunization, such as weak D type 2 and partial DVI, were detected.CONCLUSION: The confirmatory RhD test using the gel test for indirect antiglobulin testing represents a breakthrough in transfusion safety in this blood center. Our results emphasize the importance of assessing the blood group typing strategy in blood banks.

OBJETIVO: Vários aloanticorpos irregulares antieritrocitários, produzidos por sensibilizações a antígenos estranhos durante gestações ou transfusões, possuem importância clínica por provocarem hemólise no feto ou recém-nascido e/ou no receptor de sangue. Diante disso, fizemos uma análise prospectiva exclusiva de pacientes atendidos nos serviços de emergência clínica e cirúrgica, correlacionando as aloimunizações aos dados clínicos e epidemiológicos. MÉTODOS: Amostras sanguíneas de 143 pacientes, com pesquisa inicial de anticorpos negativa, foram coletadas até 15 meses após transfusões de concentrados de hemácias (CH), submetidas a Pesquisas de Anticorpos Irregulares (PAI) e, quando o resultado fosse positivo, à identificação e titulação seriada do(s) aloanticorpo(s). Para comparar proporções, foi empregado Teste Exato de Fisher e Odds Ratio. RESULTADOS: Dos pacientes estudados, 15 (10,49%) produziram aloanticorpos em um período de seis meses, com o título decaindo e negativando até 15 meses em 60% dos aloimunizados. Os aloanticorpos anti-K e os dirigidos contra antígenos do sistema Rh foram os mais frequente, o maior título foi de 1:32 (anti-K) e houve evidente correlação com o número de transfusões. CONCLUSÃO: Diante da alta ocorrência de aloanticorpos antieritrocitários de importância clínica em indivíduos transfundidos em serviço de emergência clínica e cirúrgica, propomos estender a fenotipagem e compatibilização pré-transfusional para os antígenos C, c, E, e (sistema Rh) e K (sistema Kell) para todos os pacientes com cirurgias programadas e/ou com eventos clínicos agudos que não necessitem de transfusões emergenciais.

BACKGROUND: Several irregular red blood cell alloantibodies, produced by alloimmunization of antigens in transfusions or pregnancies, have clinical importance because they cause hemolysis in the fetus and newborn and in transfused patients. OBJECTIVE: a prospective analysis of patients treated by the surgical and clinical emergency services of Hospital de Clínicas of the Universidade Federal do Triângulo Mineiro (HC/UFTM), Brazil was performed to correlate alloimmunization to clinical and epidemiological data. METHODS: Blood samples of 143 patients with initial negative antibody screening were collected at intervals for up to 15 months after the transfusion of packed red blood cells. Samples were submitted to irregular antibody testing and, when positive, to the identification and serial titration of alloantibodies. The Fisher Exact test and Odds Ratio were employed to compare proportions. RESULTS: Fifteen (10.49%) patients produced antibodies within six months of transfusion. However, for 60% of these individuals, the titers decreased and disappeared by 15 months after transfusion. Anti-K antibodies and alloantibodies against antigens of the Rh system were the most common; the highest titer was 1:32 (anti-K). There was an evident correlation with the number of transfusions. CONCLUSIONS: Given the high incidence of clinically important red blood cell alloantibodies in patients transfused in surgical and clinical emergency services, we suggest that phenotyping and pre-transfusion compatibilization for C, c, E, e (Rh system) and K (Kell system) antigens should be extended to all patients with programmed surgeries or acute clinical events that do not need emergency transfusions.

OBJETIVO: Este estudo teve como objetivos: 1) implementar a genotipagem para os antígenos S, s e U do sistema de grupo sanguíneo MNS na Fundação Hemominas e 2) avaliar pela primeira vez em uma população miscigenada de Minas Gerais, Brasil a ocorrência de polimorfismos do gene GYPB relacionados aos fenótipos U- e U+var, assim como a deleção de GYPB. Os antígenos S, s e U podem ocasionar reações transfusionais e doença hemolítica perinatal. A genotipagem é uma ferramenta útil na imuno-hematologia, principalmente quando a fenotipagem não pode ser realizada. MÉTODOS: 96 amostras de doadores de sangue e pacientes com doença falciforme previamente fenotipadas para os antígenos S, s e U foram selecionadas. As técnicas AS/PCR e ensaio combinado AS/PCR - RFLP foram empregadas para identificar os alelos GYPB*S, GYPB*s e as variantes GYPB(P2) e GYPB(NY), bem como a deleção do gene GYPB. RESULTADOS: Os resultados da genotipagem alelo-específica GYPB*S e GYPB*s foram 100% concordantes em relação aos fenótipo S+ (n = 56), s+ (n = 60) e s- (n = 35). Entretanto, o alelo GYPB*S, em associação com a variante GYBP(P2), foi detectado em 17,5% das amostras S- (n = 40), o que revela a importância da avaliação desta variante em nossa população. Entre as amostras S-s- avaliadas (n = 10), 60% apresentaram deleção do gene GYPB, e 40% apresentaram GYPB (P2) em homo ou hemizigose. CONCLUSÃO: A genotipagem é uma estratégia eficaz na inferência dos fenótipos S, s e U na população miscigenada de Minas Gerais, podendo contribuir para a segurança transfusional.

OBJECTIVE: To implement genotyping for S, s and U antigens of the MNS blood group system at the Fundação Hemominas and to evaluate the occurrence of GYPB gene polymorphisms associated with the U- and U+var phenotypes and deletion of the GYPB gene for the first time in an admixed population of Minas Gerais, Brazil. The S, s and U antigens can cause transfusion reactions and perinatal hemolytic disease. Genotyping is a useful tool in immunohematology, especially when phenotyping cannot be performed. METHODS: Ninety-six samples from blood donors and patients with sickle cell disease previously phenotyped for the S, s and U antigens were selected. Allele-specific primer polymerase chain reaction (ASP-PCR) and polymerase chain reaction -restriction fragment length polymorphism (PCR-RFLP) assays were employed to identify the GYPB*S and GYPB*s alleles and the GYPB(P2) and GYPB(NY) variants, as well as deletion of the GYPB gene. RESULTS: The results of allele-specific genotyping (GYPB*S and GYPB*s) were totally in agreement with the phenotyping of S+ (n = 56), s+ (n = 60) and s- (n = 35) samples. However, the GYPB*S allele, in association with the GYPB(P2) variant, was detected in 17.5% of the S- samples (n = 40), which shows the importance of assessing this variant in the Brazilian population. Of the S-s- samples (n = 10), 60% had the deletion of the GYPB gene and 40% were homozygous or hemizygous for the GYPB(P2) variant. CONCLUSION: Genotyping was an effective strategy to infer the S, s, and U phenotypes in the admixed population from Minas Gerais (Brazil) and may contribute to transfusion safety.